Alkali metal alkylsiliconates, alkali metal silicates, mixtures thereof and organosilicon compounds which contain alkoxy groups and are dissolved in organic solvents or in water or aqueous dispersions of organosilicon compounds containing alkoxy groups have been injected into masonry materials to combat rising dampness.
Leaflet 1-86, published by the masonry damp-removal section of the Wissenschaftlich-Technischer Arbeitskreis fur Denkmalpflege und Bauwerksanierung e.V. (Scientific-Technical Study Group for Monument Preservation and Building Restoration e.V.), Munich, recommends preliminary rinsing of bore-holes with, for example, lime water before water-soluble compositions, such as alkali metal alkyl siliconates, alkali metal silicates and silanes, are injected therein. The water-soluble active compounds present in the injecting agents are precipitated by the calcium ions introduced into the wall, and gel.
The use of alkali metal alkyl siliconates dissolved in water, optionally, as described in GB-A-1,177,662 (C.T. Kyte; published on Jan. 14, 1970 to Gallwey Chemical Co. Ltd., Marlow, Great Britain), in combination with alkali metal silicate, is accompanied by the appearance in the masonry of water-soluble, hygroscopic carbonates capable of efflorescing. In thick masonry, the ingress of CO.sub.2 from the air, which is necessary for the active compound to form, is much more difficult.
The water-soluble silanes which are suitable as the active compound in injecting agents for combating rising dampness in masonry, such as methylsilane-trismethyl glycolate, are injurious to health, and may even cause malformations.
GB-A-1,374,611 (J. G. Coombs Price; published on Nov. 20, 1974 to Dow Corning Ltd., London) describes a method of forming a vapor-tight barrier in masonry, in which organosilicon compounds containing alkoxy groups dissolved in organic solvents are introduced through holes in the masonry. The use of organic solvents increases the risk of fire and environmental pollution, especially in inhabited buildings.
U.S. Pat. No. 4,661,551 (H. Mayer et al.; published on Apr. 28, 1987 to Wacker-Chemie GmbH, Munich) describes the use of a highly dispersed water-diluted composition comprising isooctyltrimethoxysilane, a salt of a water-soluble acid and a nitrogen-containing organopolysiloxane, n-hexanol and glacial acetic acid for forming a barrier against rising dampness in a brick wall. This composition spreads rapidly in the damp masonry and reacts with the masonry to form a barrier which prevents further rising of the water. However, if the masonry is old, this composition does not perform well.
Therefore, it is an object of the present invention to provide a process for treating old masonry to impart water repellency thereto. Another object of the present is to provide a process for impregnating masonry to impart water repellency thereto which does not present a health hazard. A further object of the present invention is to provide a process for impregnating old masonry with water diluted compositions.